import * as Cesium from 'cesium'

const defaultColor = Cesium.Color.TRANSPARENT;
const defaultImage = "src/assets/images/cesium/arrow.png";
const defaultImageimageW = 100
const defaultAnimation = false
const defaultDuration = 1000;

export class ImageLineMaterial {
    constructor(opt) {
        opt = Cesium.defaultValue(opt, Cesium.defaultValue.EMPTY_OBJECT);
        this._definitionChanged = new Cesium.Event();
        // 定义材质变量
        this._color = undefined;
        this._colorSubscription = undefined;
        this._backgroundColor = undefined;
        this._backgroundColorSubscription = undefined;
        this._image = undefined;
        this._imageSubscription = undefined;
        this._imageW = undefined;
        this._imageWSubscription = undefined;
        this._animation = undefined;
        this._animationSubscription = undefined;
        this._duration = undefined;
        this._durationSubscription = undefined;
        // 变量初始化
        this.color = opt.color || defaultColor; //颜色
        this.backgroundColor = opt.backgroundColor || defaultColor; //颜色
        this._image = opt.image || defaultImage; //材质图片
        this.imageW = opt.imageW || defaultImageimageW;
        this.animation = opt.animation || defaultAnimation;
        this.duration = opt.duration || defaultDuration;
        this._time = undefined;
    }
    // 材质类型
    getType(time) {
        return "ImageLine";
    }
    // 这个方法在每次渲染时被调用，result的参数会传入glsl中。
    getValue(time, result) {
        if (!Cesium.defined(result)) {
            result = {};
        }
        result.color = Cesium.Property.getValueOrClonedDefault(this._color, time, defaultColor, result.color);
        result.backgroundColor = Cesium.Property.getValueOrClonedDefault(this._backgroundColor, time, defaultColor, result.backgroundColor);
        result.image = this._image;
        result.imageW = this._imageW;
        result.animation = this._animation;
        if (this._time === undefined) {
            this._time = new Date().getTime();
        }
        result.time = ((new Date().getTime() - this._time) % this._duration) / this._duration;
        return result;
    }
    equals(other) {
        return this === other ||
            other instanceof ImageLineMaterial && Cesium.Property.equals(this._color, other._color) && Cesium.Property.equals(this._backgroundColor, other._backgroundColor);
    }
}

Object.defineProperties(ImageLineMaterial.prototype, {
    isConstant: {
        get: function get() {
            return false;
        }
    },
    definitionChanged: {
        get: function get() {
            return this._definitionChanged;
        }
    },
    color: Cesium.createPropertyDescriptor('color'),
    backgroundColor: Cesium.createPropertyDescriptor('backgroundColor'),
    image: Cesium.createPropertyDescriptor('image'),
    imageW: Cesium.createPropertyDescriptor('imageW'),
    animation: Cesium.createPropertyDescriptor('animation'),
    duration: Cesium.createPropertyDescriptor('duration'),
});

Cesium.Material._materialCache.addMaterial("ImageLine", {
    fabric: {
        type: "ImageLine",
        uniforms: {
            // uniforms参数跟我们上面定义的参数以及getValue方法中返回的result对应，这里值是默认值
            color: new Cesium.Color(1, 0, 0, 1.0),
            backgroundColor: new Cesium.Color(0, 0, 0, 0.0),
            image: '',
            imageW: 1,
            animation: false,
            duration: 30,
            time: 0
        },
        // source编写glsl，可以使用uniforms参数，值来自getValue方法的result
        source: `#extension GL_OES_standard_derivatives : enable
czm_material czm_getMaterial(czm_materialInput materialInput)
{
    czm_material material = czm_getDefaultMaterial(materialInput);
    vec2 st = materialInput.st;
    float s = st.s/ (abs(fwidth(st.s)) * imageW * czm_pixelRatio);
    s = s-time;//增加运动效果
    float t = st.t;
    vec4 colorImage = texture(image, vec2(fract(s), t));
    material.diffuse = colorImage.rgb; 
    return material;
}

`
    },
    translucent: function translucent() {
        return true;
    }
});
// 写到Cesium对象上，就可以像其他MaterialProperty一样使用了
// Cesium.Material.ImageLineType = 'ImageLine'
// Cesium.ImageLineMaterial2DProperty = ImageLineMaterial
